Respiratory mask



FIG. 1 is a perspective view of a respiratory mask showing the new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a right side elevation view thereof (the left side elevation view is a mirror image of FIG. 6).

The dash-dash type broken lines shown in the drawing views are included for the purpose of showing environmental subject matter that forms no part of the claimed design. 

CLAIM The ornamental design for a respiratory mask, as shown and described. 